Not Applicable.
Not Applicable.
The invention refers to a rail brake element, in particular in connection with rail brake buffer blocks. Rail brake elements of the kind mentioned above are known from DE 24 53 223 or DE 34 22 230. The known elements include two clamping plates C-shaped in cross section and adapted to engage a rail head from opposite sides. Lower leg portions of the clamping plate engage the lower surfaces of the rail head and are provided with a braking lining. The upper leg portions of the clamping plates lie on tapered or oblique surfaces of a braking block element. The lower surface of the block element is supported by the upper surface of the rail head. At least one clamping bolt interconnects the clamping plates and presses the clamping plates towards the rail head and against the braking block so that a braking effect occurs if the braking element is displaced by a vehicle on the rail. Such a displacement preferably takes place by a buffer block which is supported on the rails and may be easily displaced or wherein braking elements are integrated. It is also known to provide further braking elements in front or in the rear of the buffer block in order to increase the braking capacity. Normally, the braking elements are spaced from each other so that upon a buffing the static friction of the individual braking elements is overcome one after the other. As known, the static friction is at least the double of the sliding friction.
Usually, the rails undergo a wear. This can result in a wear amount of the half of the height of the rail head until it is replaced. When manufacturing the braking blocks for the braking elements, the height of the rail head is measured with a tolerance of maximum 2 mm. Since the wear normally is in a wider range, it is necessary to provide different braking blocks for different heights of the rail heads. Only by a correct seat of the braking element the necessary and calculated braking capacity is guaranteed. Further tolerances may occur through unprecise measuring methods, by the manufacturing, and the assembling of the individual parts.
The invention provides a braking element wherein independent of the height of the rail head a uniform braking block can be used.
In the braking element according to the invention the upper tapered surfaces have an inclination of at least 20xc2x0, preferably of approximately 25xc2x0 relative to a horizontal plane. The braking block and the clamping plates are dimensioned such that the upper end of the upper leg portions of the clamping plate are significantly spaced from the upper edge of the associated tapered surface.
The C-shaped clamping plates are conventionally standardized, i.e. they have uniform sizes. In case of a wear of the rail head the upper leg portion automatically moves along the upper tapered surface which was not possible with conventional braking blocks. Conventional braking blocks have a relative small angle of inclination of approximately 10 to 15xc2x0. This inclination was regarded as necessary in order to achieve a sufficient wedging effect by the associated leg portions of the clamping plate. Known clamping blocks are provided with an abutment edge defined by a step-shaped elevation of the braking block and which serves to indicate the wear. Already with a small wear the ends of the upper leg portions of the clamping plates reach the abutment edge.
In the braking element according to the invention the braking block is provided with a significant larger inclination which may be up to 25xc2x0. It has been found out that also with such an inclination a sufficient wedging effect is achieved to arrive at the necessary clamping and braking force. The larger angle of inclination and the corresponding distance between the ends of the upper clamping legs and the upper edges of the tapered surfaces allow a significant wear of the rail head. Differences in the height of 5 mm and more can be met without the need of a different braking block having modified dimensions.
The braking block according to the invention, thus, can be used for a large range of wear of different rails and nevertheless guarantees a sufficient seat and a satisfactory braking effect. The universal application of the braking block reduces the expenses for the manufacture and the inventory if compared with the prior art. A further advantage is to be seen in that despite of tolerances by the manufacture of the parts and the assembling thereof the necessary security of the braking element is achieved.